By an act of January 12, 1705/1706, the officers of Philadelphia's Corporation were empowered to appoint annually "one, two, or more" Overseers of the Poor who were to lay and collect a poor tax and distribute its proceeds among the City's indigent. In 1735 the Assembly placed the newly erected Alms House and House of Employment in the Corporation's control and required the Overseers to provide funds for its operation out of the poor tax, leaving them only the administration of direct relief payments. In 1749 the Overseers were incorporated; in 1766 the Assembly also incorporated The Contributors to the Relief and Employment of the Poor of the City of Philadelphia, the District of Southwark, and the Townships Northern Liberties, Moyamensing and Passyunk a body of citizens who were given authority to erect a new Alms House and to administer it through a Board of Managers appointed by them annually; the funds for its operation were still directed to be provided by the Overseers out of the poor tax. Since no provision was made for adding members to their body the Contributors' eventual failure to function led to the Alms House's transfer in 1788 to the Overseers of the City, Southwark, Moyamensing and the Northern Liberties who were newly incorporated under the title of the Guardians of the Poor. In 1782 and 1791 Passyunk and Moyamensing respectively were removed from this system of poor relief. As the Guardians' jurisdiction was not countywide, similar functions were performed by the Overseers of the Poor of Oxford and Lower Dublin Townships, Germantown, Bristol, and Roxborough and Manayunk. The Consolidation of the City and County in 1854 left these Overseers' authority intact and abolished the Guardians' power to levy the poor tax, directing instead that their operations be financed through an annual appropriation of City Councils. The Guardians of the Poor were abolished by the Bullitt Bill in 1887 and their functions and property were transferred to the Bureau of Charities in the then established Department of Charities and Correction.

Although court decisions of 1879 and 1880 determined that the Guardians of The Poor were actually a department of City government under the terms of The Consolidation Act of 1854, all of their records series have been grouped here under the County of Philadelphia as those decisions had no discernible effect upon the Guardians' functions or the form and content of their records. [Williamsport Poor Observers v. Philadelphia Poor Guardians, 7 W.N.C. 222 (1879); Mathews v. Philadelphia, 93 Pa. 147 (1880).]